Alphonso Jackson makes brief statement, releases letter in Washington.
"There are times when one must attend more diligently to personal and family matters...." Read letter here.
Had come under fire for allegedly steering federal housing contracts to political allies.
Obama responds: Resignation "serves as a stark reminder of what's at stake in this election." Read full statement.
Clinton responds: "Secretary Jackson's resignation ends a tenure at HUD marked by an indifference to Congressional oversight powers, cronyism, and corrupt contracting practices...."Read full statement.
